The present invention relates to a module for printing postage value, or other information, on an envelope in a high speed mass mail processing and inserting system. Within the postage printing module, the motion of the envelope is controlled to allow high envelope throughput, even if the postage printing device operates at a lower velocity than other parts of the system.
Inserter systems such as those applicable for use with the present invention, are typically used by organizations such as banks, insurance companies and utility companies for producing a large volume of specific mailings where the contents of each mail item are directed to a particular addressee. Also, other organizations, such as direct mailers, use inserts for producing a large volume of generic mailings where the contents of each mail item are substantially identical for each addressee. Examples of such inserter systems are the 8 series and 9 series inserter systems available from Pitney Bowes Inc. of Stamford Conn.
In many respects, the typical inserter system resembles a manufacturing assembly line. Sheets and other raw materials (other sheets, enclosures, and envelopes) enter the inserter system as inputs. Then, a plurality of different modules or workstations in the inserter system work cooperatively to process the sheets until a finished mail piece is produced. The exact configuration of each inserter system depends upon the needs of each particular customer or installation.
Typically, inserter systems prepare mail pieces by gathering collations of documents on a conveyor. The collations are then transported on the conveyor to an insertion station where they are automatically stuffed into envelopes. After being stuffed with the collations, the envelopes are removed from the insertion station for further processing. Such further processing may include automated closing and sealing the envelope flap, weighing the envelope, applying postage to the envelope, and finally sorting and stacking the envelopes.
Current mail processing machines are often required to process up to 18,000 pieces of mail an hour. Such a high processing speed may require envelopes in an output subsystem to have a velocity in a range of 80-85 inches per second (ips) for processing. Consecutive envelopes will nominally be separated by a 200 ms time interval for proper processing while traveling through the inserter output subsystem. At such a high rate of speed, system modules, such as those for sealing envelopes and putting postage on envelopes, have very little time in which to perform their functions. If adequate control of spacing between envelopes is not maintained, the modules may not have time to perform their functions, envelopes may overlap, and jams and other errors may occur. In particular, postage meters are time sensitive components of a mail processing system. Meters must print a clear postal indicia on the appropriate part of the envelope to meet postal regulations. The meter must also have the time necessary to perform the necessary bookkeeping and calculations to ensure the appropriate funds are being stored and printed.
A typical postage meter currently used with high speed mail processing systems has a mechanical print head that imprints postage indicia on envelopes being processed. Such conventional postage metering technology is available on Pitney Bowes R150 and R156 mailing machines using model 6500 meters. The mechanical print head is typically comprised of a rotary drum that impresses an ink image on envelopes traveling underneath. Using mechanical print head technology, throughput speed for meters is limited by considerations such as the meter""s ability to calculate postage and update postage meter registers, and the speed at which ink can be applied to the envelopes. In most cases, solutions using mechanical print head technology have been found adequate for providing the desired throughput of approximately five envelopes per second to achieve 18,000 mail pieces per hour.
However, use of existing mechanical print technology with high speed mail processing machines presents some challenges. First, some older mailing machines were not designed to operate at such high speeds for prolonged periods of time. Accordingly, solutions that allow printing to occur at lower speeds may be desirable in terms of enhancing long term mailing machine reliability.
Another problem is that many existing mechanical print head machines are configured such that once an envelope is in the mailing machine, it is committed to be printed and translated to a downstream module, regardless of downstream conditions. As a result, if there is a paper jam down stream, the existing mailing machine component could cause even more collateral damage to envelopes within the mailing machine. At such high rates, jams and resultant damage may be more severe than at lower speeds. Accordingly, improved control and lowered printing speed, while maintaining high throughput rate in a mechanical print head mailing machine could provide additional advantages.
Controlling throughput through the metering portion of a mail producing system is also a significant concern when using non-mechanical print heads. Many current mailing machines use digital printing technology to print postal indicia on envelopes. One form of digital printing that is commonly used for postage metering is thermal inkjet technology. Thermal inkjet technology has been found to be a cost effective method for generating images at 300 dpi on material translating up to 50 inches per second. Thus, while thermal inkjet technology is recognized as inexpensive, it is difficult to apply to high speed mail production systems that operate on mail pieces that are typically traveling in the range of up to 80 ips in such systems.
As postage meters using digital print technology become more prevalent in the marketplace, it is important to find suitable substitutes for the mechanical print technology meters that have traditionally been used in high speed mail production systems. This need for substitution is particularly important as it is expected that postal regulations will require phasing out of older mechanical print technology meters, and replacement with more sophisticated meters. Although digital print technology exists that is capable of printing the requisite 300 dpi resolution on paper traveling at 80 ips, such devices are so expensive as to be considered cost prohibitive. Accordingly, it would be beneficial to have a solution that would allow lower velocity digital print technology, like thermal inkjet technology, to be utilized with the high speed mail production systems.
Some systems that have been available from Pitney Bowes for a number of years address some related issues. These systems utilize R150 and R156 mailing machines using 6500 model postage meters installed on an inserter system. The postage meters operate at a slower velocity than that of upstream and downstream modules in the system. When an envelope reaches the postage meter module, a routine is initiated within the postage meter. Once the envelope is committed within the postage meter unit, this routine is carried out without regard to conditions outside the postage meter. The routine decelerates the envelope to a printing velocity. Then, the mechanical print head of the postage meters imprints an indicia on the envelope. After the indicia is printed, the envelope is accelerated back to close to the system velocity, and the envelope is transported out of the meter.
One problem with this current solution is that the conventional postage meters are inflexible in adjusting to conditions present in upstream or downstream meters. For example, if the downstream module is halted as a result of a jam, the postage meter will continue to operate on whatever envelope is within its control. This often results in an additional jam, and collateral damage, as the postage meter attempts to output the envelope to a stopped downstream module.
Another problem with the current solution is that it is very sensitive to gaps between consecutive envelopes. This is because the R150 and R156 mailing machines are a bit too long to have time to carry out the routine on the envelopes, and to still have some margin for error in the arrival of a subsequent envelope. As such, a module with better space utilization and less sensitivity to gap variations is desirable.
The present application describes a system and a method to control the motion of envelopes within a postage printing module to accommodate the use of slower print techniques (digital or mechanical) in attempting to achieve high throughput in a mail processing system.
The system transports a first envelope at a nominal transport velocity to the postage printing module embodying the present invention. The postage printing module receives the envelope at the nominal transport velocity. When the envelope has passed completely into the control of the postage printing module it is decelerated to a predetermined lower print velocity for printing an image of a predetermined length. After the printing is complete the envelope is accelerated back to the transport speed and transported to a downstream module. None of the intervals of deceleration, low print velocity, or acceleration may occur while an envelope in the postage printing module is also in the control of another module.
In the preferred embodiment, the deceleration is activated by a sensor sensing the presence of the envelope at a trigger point. Further sensors at the upstream and downstream modules can be used to verify that no envelopes are under the shared control of the postage printing module and another module.
In another preferred embodiment, the print head is geared to operate in synchronism with the print transport, such that an image will not be distorted if there is a variation in print velocity.
The preferred system and method also provide a way to ensure that correct displacement is maintained between subsequent envelopes under the control of the invention in the event of a stop and/or restart of the system resulting from an exception condition, such as an envelope jam. When an envelope is within the print transport during an exception condition, the envelope must be decelerated to a stop, so as not to create further jams or collateral damage. In most modules in the system, a linear uniform deceleration is preferred to minimize disruption of the desired spacing between mail pieces being processed.
For the postage printing module, however, optimal performance using the present invention may require that deceleration not occur in the same uniform linear fashion as the rest of the system. Rather, deceleration is preferably controlled to maintain the relative displacement of envelopes in the postage printing module with respect to upstream and downstream modules. Because displacement varies in that module during normal operation, a uniform stopping and starting of the print module to mirror other modules will result in envelope spacing different than originally intended. Such changing in envelope gaps may result in further jams or misprocessing.
For this reason, the deceleration and acceleration resulting from the exception condition is controlled to maintain relative displacements as those displacements would have been if the exception condition had not occurred. To achieve this result, a controller in the print module controls the displacement of the print module according to a predetermined algorithm. This algorithm relates displacements of the print module with other modules for segments of the motion profile as they would have been executed during normal operation. During the exception condition, deceleration and acceleration of the print module is thus controlled as a predetermined function, or set of functions, of the displacements in other transport modules. The appropriate function is determined as a result of the position of the envelope in the print module during the course of the exception condition.
This displacement mapping functionality of the preferred embodiment operates cooperatively with the gearing of the print head mechanism to the print transport. In that preferred embodiment, stopping and restarting of the print module may not affect printing of an image on the envelope, even if a printing operation had already begun at the time of the stoppage.
The principles discussed herein are also applicable to a system condition in which the system is stopped without the occurrence of any problems. For example, the present invention may be applied in a situation where an operator simply wishes to turn off the system in order to take a lunch break, without waiting for the job to finish. Using the present invention, the process of routine stopping and starting of the system is simplified, and the risk of errors occurring from such stopping and starting is reduced. Therefore, it will be understood that the present invention applies equally to all stoppage conditions. Stoppage conditions include errors and exception conditions, as well as routine starting and stopping.
Further details of the present invention are provided in the accompanying drawings, detailed description and claims.